The Bonney Lake man, whose nickname is “Bigfoot,” faces the likelihood of spending the next two decades in prison after pleading guilty on Tuesday to seven felonies, including manslaughter, kidnapping, robbery, burglary and assault.

Frohs, 45, was part of a heavily armed band of criminals who held a Marysville husband and wife at gunpoint inside their home Dec. 1, 2011.

The crew, which included members of outlaw motorcycle and prison gangs, was looking to retaliate against two men who had ripped off a drug dealer they knew. They thought the pair would be inside the home, but they were not.

The robbery took a fatal turn when Frohs mistook one of his own group as a rival. He shot Patrick “Bucky” Buckmaster, 30, in the head when the Tacoma man entered the Marysville home wearing what prosecutors described as a “Jason” goalie mask in reference to the horror movie “Friday the 13th.”

Frohs initially was charged with second-degree murder, but the charge was amended to first-degree manslaughter during plea negotiations.

Prosecutors and Frohs’ defense attorney said they are recommending a 21-year sentence, which includes a penalty for committing the crimes while armed with a firearm.

In his written plea, Frohs said he did not intend to cause Buckmaster’s death and “I am sorry that he is gone.”

The robbers scattered after the shooting as did the couple who had been threatened.

Some of the robbers returned, packed Buckmaster’s body into the trunk of a car and drove to Denny’s. He later was buried in a shallow grave in east Snohomish County. His body was discovered about a month later.

Nearly a dozen men were implicated in the robberies. The majority have pleaded guilty or already been convicted at trials.

Several Snohomish County Sheriff’s Office detectives watched Tuesday’s plea hearing. Frohs was rolled into Snohomish County Superior Courtroom in a wheelchair. His attorney said Frohs is dealing with medical issues.

Deputy prosecutor Mara Rozzano said Frohs previously had been convicted of taking part in a home invasion robbery in King County. In that 1994 case, he was convicted of assault, burglary, extortion and robbery. He was released from prison in 2009.

Sentencing could occur as early as Friday. Prosecutors will ask if that will provide the victim’s family enough time to prepare a statement for the judge to consider at sentencing.